Studies on the structural, electrical and magnetic properties of LaCrO_3, LaCr_(0.5)Cu_(0.5)O_3 and LaCr_(0.5)Fe_(0.5)O_3 by sol-gel method

摘要

The structural, electrical and magnetic properties of LaCr_(0.5)M_(0.5)O_3 (M = Cr~(3+), Cu~(2+) and Fe~(3+)) synthesized by a sol-gel technique were studied. The X-ray diffraction pattern shows the structure to be orthorhombic and the size of the particles is around 100 nm as seen from the TEM images. The effects of Cu~(2+) and Fe~(3+) on the electrical properties of LaCrO_3 were studied using impedance spectroscopy at room temperature (RT). The properties of LaCr_(0.5)Cu_(0.5)O_3 were studied over a wide range of temperature from RT to 533 K. A maximum conductivity of 1.7 × 10~(-3)S cm~(-1) was observed for LaCr_(0.5)Cu_(0.5)O_3 at a measured temperature of 533 K. The impedance spectra indicate a negative temperature coefficient of resistance (NTCR) and also imply the conduction is through bulk of the material. The magnetic studies performed using a SQUID magnetometer interpret the antiferromagnetically ordered LaCrO_3 to behave ferromagnetically on the addition of Cu~(2+) and Fe~(3+), and the magnetization was found to be enhanced in the LaCr_(0.5)Fe_(0.5)O_3.